Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Patent
1998-06-30
2000-07-11
Griffin, Steven P.
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
502302, 502325, 502345, 502347, 502352, 502355, 4232135, 4232137, B01J 2104, B01J 2904, B01D 5394
Patent
active
060872950
ABSTRACT:
Removal of carbon monoxide, hydrocarbons, and nitrogen oxides from the exhaust gas from lean-burn, diesel and other engines which produce exhaust gases containing excess oxygen is provided by a multi-component catalyst having at least two catalytic components, each capable of reducing nitrogen oxides within a range of exhaust gas temperatures that is different from the range of exhaust gas temperatures within which each other component is capable of reducing nitrogen oxides. Oxidation of the remaining reducing gases is also accomplished. One example of a two catalytic component catalyst of this invention has a first component of Au supported on alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 600.degree. C. and 900.degree. C., and a second component of Pt supported on Y-zeolite, which reduces nitrogen oxides at exhaust gas temperatures below 600.degree. C.; an example of a three catalytic component catalyst of this invention has a first component of CoO supported on .gamma.-alumina, which reduces nitrogen oxides at exhaust gas temperatures above about 475.degree. C., a second component of an alloy of Pt, Rh and Co supported on BaO.sub.2 -stabilized .delta.-alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 315.degree. C. and about 475.degree. C. and a third component of an alloy of Pt and Rh supported on .alpha.-alumina, which reduces nitrogen oxides at exhaust gas temperatures between about 200.degree. C. and about 425.degree. C. A method of selecting such catalysts is also provided.
REFERENCES:
patent: 5010051 (1991-04-01), Rudy
patent: 5531972 (1996-07-01), Rudy
patent: 5727385 (1998-03-01), Hepburn
Kung et al. "Selective Reduction of NO.sub.x by Propene Over Au/.gamma.-Al.sub.2 O.sub.3 Catalysts" 11th International Congress on Catalysis--40th Anniversary Studies in Surface Science and Catalysis, vol. 101, Elsevier Science B. V. J. W. Hightower et al. (Editors), pp. 701-710, Jun. 30-Jul. 5, 1996.
Haneda et al. "Ga.sub.2 O.sub.3 /Al.sub.2 O.sub.3 Prepared by Sol-Gel Method . . . " Chemistry Letters, pp. 181-182, 1998 (No Month).
Kharas Karl C. C.
Robota Heinz J.
ASEC Manufacturing
Griffin Steven P.
Vanoy Timothy C
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